The screen is a page of the chip's own memory. Nothing draws it but this page.
Arrow keys or WASD. One byte, written into the chip's memory between two steps.
Every gate is a switch that exists on this die, and it conducts exactly when its own control line is high on the chip running this game. Nothing simulates a clock phase. The letter is the channel that is open right now.
A frame costs 600 half-cycles, about 0.3 ms of chip time. Everything else is the round trip: the whole machine travels to the engine and back on every frame, because the server keeps no sessions. The chip is not the bottleneck by three orders of magnitude.